Biological decolorization of dye solution containing malachite green by Pandoraea pulmonicola YC32 using a batch and continuous system
Introduction
Malachite green (MG) is a triphenylmethane dye that is used extensively in the textile and fish farming industries as a biocide. It is toxic to human beings, affecting both the immune and reproductive system [1], and has a highly toxic effect on freshwater fish following either acute or chronic exposure [2]. Consequently, any discharge of an MG-containing solution into a river or stream will adversely affect on the exposed aquatic organisms. Although, the use of MG for controlling fungal infections and ectoparasites in the aquaculture industry is prohibited in the USA because of its carcinogenic nature [3], it is still used in some areas of the world because of its low cost [4]. As there is a significant health risk to humans who eat fish contaminated with MG, it is very important to establish a method to remove this substance from water/solutions.
A number of studies have been carried out in which physico-chemical methods, such as adsorption, precipitation, photodegradation, osmosis, and membrane filtration, have been used to treat MG. However, such methods have proved to be methodologically demanding, relatively inefficient, and time-consuming [5], [6], [7]. Focus has therefore turned to biological processes as a viable alternative as such systems are cost-effective and environmentally friendly, and they produce less sludge [8], [9], [10]. However, there was no MG degradation pathway ever discussed in these studies.
A variety of organisms have been identified as being capable of decolorizing and degrading MG, including a microalgae (Cosmarium sp.) [11], yeast (Saccharomyces cerevisiae) [4], and fungus (Ischnoderma resinosum) [12]. The use of the bacteria Kurthia sp. and Kocuria rosea to treat MG were reported as well [13], [14]. However, few studies have been made on the use of bacteria to treat MG in a “continuous” system.
Pandoraea pulmonicola was first identified by Coenye et al. [15]. The cells of P. pulmonicola are Gram-negative, non-sporulating. They are motile by means of a single polar flagellum. Catalase activity is present and P. pulmonicola can assimilate caprate and dl-lactate. Growth is observed at 30 and 37 °C. Although there are no published data currently available on its efficiency to biodegrade MG, preliminary experiments carried out in our laboratory revealed that this specie or strain has a high capability to degrade MG. In addition, P. pulmonicola can be cultured easily in culture medium.
The aim of the study reported here was to isolate MG-degrading microorganisms from contaminated soil nearby a textile plant, determine the basic physiological characteristic of the isolated strain, and provide further details on P. pulmonicola YC32 in terms of its capability to degrade MG. The effect of various operating parameters (initial concentration of MG, pH, and cell numbers of P. pulmonicola YC32) on MG removal in a batch system was evaluated, and the primary metabolic pathway during the biodegradation process was established. The removal characteristics of the immobilized P. pulmonicola YC32 to degrade MG in a continuous system were also investigated.
Section snippets
Chemicals
All the chemicals used in our experiment were analytical grade. Malachite green (MG, purity ≥ 96%) was obtained from Sigma–Aldrich, Inc.
Microorganisms and cultivation
Soil samples were collected from contaminated sites around a textile plant in southern Taiwan. Each soil sample (10 g) was mixed with 200 ml sterile basal mineral medium [BMM (per liter distilled water): 4.8 g K2HPO4, 1.2 g KH2PO4, 1 g NH4NO3, 0.25 g MgSO4·7H2O, 0.04 g CaCl2, 0.001 g Fe2(SO4)3] in a 300-ml flask and vortexed vigorously for 20 min [16]. A 10-ml aliquot of
Characterization of MG-degrading bacteria
The PCR amplification and sequencing procedures were according to Sandaa et al. [18] and resulted in the isolate being identified as P. pulmonicola YC32 with 98.6% similarity (GenBank accession no. AF139175). Our phylogenetic tree analysis of the isolate (Fig. 1) clearly illustrates that the isolate YC32 was has a high similarity with P. pulmonicola (AF139175): both isolate YC32 and P. pulmonicola (AF139175) are in the same cluster. P. pulmonicola YC32 was characterized as a non-sporulating
Conclusions
P. pulmonicola YC32 was not inferior to other microorganisms in terms of the decolorization of MG in batch and continuous operational systems (Table 2) regardless of various operating conditions tested. Our results show that this bacterial species is an efficient degrader of MG based on its decolorization efficiency and that this decolorization efficiency is dependent on the initial concentration of the dye and pH. The dependence of the MG degradation rate on MG concentration can be described
Acknowledgments
The work was supported by Grant NSC 97-2815-C-157-001-E from the National Science Council.
References (28)
- et al.
Decolorization of triphenylmethane dye-bath effluent in an integrated two-stage anaerobic reactor
J. Environ. Manage.
(2007) - et al.
Toxicological effects of malachite green
Aquat. Toxicol.
(2004) - et al.
A confirmatory analysis of malachite green residues in rainbow trout with liquid chromatography–electrospray tandem mass spectrometry
J. Chromtogr. B
(2007) - et al.
Adsorption of malachite green from aqueous solution onto carbon prepared from Arundo donax root
J. Hazard. Mater.
(2008) - et al.
Equilibrium, kinetics and mechanism of malachite green adsorption on activated carbon prepared from bamboo by K2CO3 activation and subsequent gasification with CO2
J. Hazard. Mater.
(2008) - et al.
Degradation of malachite green in aqueous solution by Fenton process
J. Hazard. Mater.
(2009) - et al.
Decolorization of the textile dyes by newly isolated bacterial strains
J. Biotechnol.
(2003) - et al.
Removal of malachite green by using an invasive marine alga Caulerpa racemosa var. cylindracea
J. Hazard. Mater.
(2009) - et al.
Biodegradation of dye solution containing Malachite Green: optimization of effective parameters using Taguchi method
J. Hazard. Mater.
(2007) - et al.
Biological decolorization of dye solution containing Malachite Green by microalgae Cosmarium sp.
Bioresour. Technol.
(2007)
Decolorization of triphenylmethane dyes and textile and dye-stuff effluent by Kurthia sp.
Enzyme Microb. Technol.
Decolorization studies of synthetic dyes using Phanerochaete chrysosporium and their kinetics
Process. Biochem.
Application of biosorption for the removal of organic pollutants: a review
Process. Biochem.
Continuous fixed bed biosorption of reactive dyes by dried Rhizopus arrhizus: determination of column capacity
J. Hazard. Mater.
Cited by (84)
Application of microbial sulfate-reduction process for sulfate-laden wastewater treatment: A review
2023, Journal of Water Process EngineeringWaste of Mytella Falcata shells for removal of a triarylmethane biocide from water: Kinetic, equilibrium, regeneration and thermodynamic studies
2020, Colloids and Surfaces B: BiointerfacesBiodegradation of malachite green by Pleurotus eryngii: a study on decolorization, mechanism, toxicity, and enzyme
2024, Environmental Science and Pollution Research